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      About Taxonomies, Thesauri and Drupal
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    <h1 id="title">
      About Taxonomies, Thesauri and Drupal
    </h1>
    <h2>
      Background Reading on Taxonomies etc.
    </h2>
    <h4>
      A Partial Bibliography
    </h4>
    <p>
      The need for shareable, interchangable, common taxonomies and
      vocabularies os a hot topic in knowledge management. Many
      partial solutions, or at least definitions of the problem,
      have been put forward. A good primer on this is <cite><a
      href="http://www.ontopia.net/topicmaps/materials/tm-vs-thesauri.html#sect-thesauri">
      Metadata? Thesauri? Taxonomies? Topic Maps!</a> Making sense
      of it all
      <br />
       By: Lars Marius Garshol</cite>
    </p>
    <p>
      Ian Dickson put out the call for <a
      href="http://www.iandickson.com/taxonomy/drupal/node/38">a
      centralized 'Taxonomy Server'</a> for Drupal, describing how
      such a project may be constructed.
    </p>
    <h2>
      Theory
    </h2>
    <p>
      According to academic papers on the subject, alternative
      vocabularies used to group different sets or axes of terms
      are labelled 'facets'. Lots of talk about it, especially in
      library circles, seems to have been done, but little is
      available on notation or communication of these concepts.
    </p>
    <p>
      A heavy-duty, but comprehensive read is The ANSI Standard <a
      href="http://www.niso.org/standards/standard_detail.cfm?std_id=814">
      Guidelines for the Construction, Format, and Management of
      Monolingual Controlled Vocabularies
      <strong>Z39-19-2005</strong></a>
    </p>
    <p>
      As it describes in section 5.3.4, "Facet Analysis" is the
      task of choosing how to construct your vocabularies, which
      terms should be grouped with which in the Drupal 'Categories'
      admin section.
    </p>
    <blockquote>
      Facets are a kind of structural metadata. Attributes that
      might be selected as facets for content objects are:
      <br />
       &bull; Topic &ndash; the subject of the content object
      <br />
       &bull; Format &ndash; the format of material (e.g., text,
      image, sound, etc.).
      <br />
       &bull; Target audience &ndash; the appropriate reader for
      the content (e.g., Children, Adults)
    </blockquote>
    <p>
      That document also contains excellent recommendations on term
      selection (Grammar, Plural form, Capitalization etc, section
      6) and illustrates a dozen alternative textual ways that
      taxonomies/thesauri may be notated (and hence could be useful
      as import/export formats).
    </p>
    <p>
      Some possible ways of rendering taxonomies are available for
      inspections from, eg <a
      href="http://www.loc.gov/rr/print/tgm1/downloadtgm1.html">Library
      of Congress: Thesaurus for Graphic Materials I: Subject
      Terms</a>
    </p>
    <h4>
      An Example Entry, LOC thesauri notation:
    </h4>
<pre>
-------------------------------
  MT: Alphabets (Writing systems)
  UF: Letters of the alphabet
  BT: Writing systems
  NT: Initials
  NT: Phonetic alphabets
  Control No.: lctgm000270
-------------------------------
</pre>
    <h5>
      <a
      href="http://www.loc.gov/rr/print/tgm1/ic.html">Mini-Glossary/explanation</a>:
    </h5>
    <dl>
      <dt>
        MT
      </dt>
      <dd>
        Term
      </dd>
      <dt>
        UF
      </dt>
      <dd>
        Used For
      </dd>
      <dt>
        BT
      </dt>
      <dd>
        Broader Term
      </dd>
      <dt>
        NT
      </dt>
      <dd>
        Narrower Term
      </dd>
    </dl>
    <p>
      Some possibly useful canonic thesauri are accessable for
      browsing (but not convenient download) at <a
      href="http://www.itsmarc.com/crs/CRS0000.htm">the Library of
      Congress</a>
      <br />
       In light of current research, the schemas used and defined
      there are positively archaic ... although they provide an
      interesting list of terms.
    </p>
    <p>
      A much larger collection of thesauri is indexed at <a
      href="http://www.taxonomywarehouse.com/">http://www.taxonomywarehouse.com/</a>
      or <a
      href="http://www.schemas-forum.org/registry/registry.html">http://www.schemas-forum.org/registry/registry.html</a>
      , including terms used by the United Nations and various
      governments.
      <br />
       ... However these are just indexes of external sites, and
      resources found there are often only 'browsable' but not
      downloadable, and when they are, are each rendered in their
      own, usually proprietary markup notation scheme! Plus various
      curious licensing restrictions ... on word lists! Obviously
      there is a need for a useful, interoperable notation scheme!
    </p>
    <p>
      <a
      href="http://thesaurus.english-heritage.org.uk/frequentuser.htm">
      The English Heritage National Monuments Record Thesauri</a>
      Collection looks like a nice clean resource, listing thesauri
      for ['Monument Types', 'Building Materials', '<a
      href="http://thesaurus.english-heritage.org.uk/thesaurus.asp?thes_no=225">
      Historic Aircraft Type</a>' and more ]. Again, it's
      browsable, not downloadable.
    </p>
    <p>
      W3C published <a
      href="http://www.w3.org/TR/2005/WD-swbp-thesaurus-pubguide-20050517/">
      Quick Guide to Publishing a Thesaurus on the Semantic Web</a>
      which <em>does</em> recommend a method, (which looks very
      much like what I ended up doing) but this doesn't seem to
      have caught on anywhere <a
      href="http://www.w3.org/2003/03/glossary-project/data/glossaries/">
      outside of their own glossary project</a> (however that's
      cool as glossaries go).
    </p>
    <p>Also from the W3C in 2008 
    (after this generation of taxonomy_xml was designed)
    there is <a href="http://www.w3.org/TR/swbp-vocab-pub/">Best Practice Recipes for Publishing RDF Vocabularies</a>.
    <br/>
    <a href="http://www.cs.vu.nl/STITCH/rameau/">Rameau (FRENCH)</a> is working example of this theory,
    and <a href="http://id.loc.gov/authorities/about.html">The Library of Congress "Authorities and Vocabularies"</a>
    now provides a public service we can hook into also!
    <br/>
    <em>Hooray for getting into standards early! 
    The taxonomy_xml lookup client was built before there were 
    <b>any</b> servers in the world for it to talk to. 
    When the servers were built a year later 
    - This client started working! (gobsmacked)</em>
    <br/>
    The Library of Congress service also publishes its data in RDFa over HTML.
    </p>
    
    <h2>
      Historical Initiatives.
    </h2>
    <p>
      ... include <a
      href="http://www.xml.com/pub/a/2003/01/22/xfml.html">XFML</a>
      (An XML representation of structured Thesauri) ... which
      appears to have totally died. Apparently giving way to
      as-yet-undefined RDF-based solutions.
    </p>
    <p>
      There once even was a Drupal XFML module, long since retired
      apparently.
    </p>
    <p>
      The syntax almost lives on in '<a
      href="http://facetmap.com/">facetmap</a>', an application and
      XML dialect that pretty much does the job, only it calls the
      multiple 'vocabularies' found in Drupal 'facets' and the
      'terms' within them 'maps' (?). Original XFML at least called
      them 'topics', which was workable.
    </p>
    <p>
      <a href="http://www.imsglobal.org/vdex/">The Vocabulary
      Definition Exchange</a> Appears to define a schema for
      representing terms and relationships within a vocabulary.
      Although it looks a bit like an awkward attempt, and I've not
      seen any actual examples of it in use.
    </p>
    <p>
      An academic thesis, <a
      href="http://www.w3.org/2001/sw/Europe/reports/thes/8.8/">Migrating
      Thesauri to the Semantic Web</a> gives some good case studies
      listing existing thesauri :
    </p>
    <ul>
      <li>
        <a
        href="http://www.nla.gov.au/apais/thesaurus/index.html">APAIS</a>
        - Australian Public Affairs Information Service , a subject
        guide to literature in the social sciences and humanities.
        Browsable (good) <em>and</em> downloadable (great)
      </li>
    </ul>
    <p>
      <a href="http://zthes.z3950.org/z3950/zthes-z3950-1.0.html">Zthes</a>
      was supposed to be the answer to <b><a href="http://www.loc.gov/z3950/agency/">ANSI/NISO Z39.50</a></b> 
      (a specification for interoperable subject searches - maintained by the Library of Congress, and closely related to Library OPAC systems)
      but it <em>never</em> got anything working or useful.
      They tried to publish <a href="http://zthes.z3950.org/schema/index.html">
      an XML schema for representing taxa</a>, and it's
      actually OK. But there are no references to anyone using it in the wild. 
      
    </p>
    <h2>
      Current Implementation of Taxonomy import/export for Drupal
      (Oct 2007)
    </h2>
    <p>
      I've referred to Wordnet/RDF + <a
      href="http://www.w3.org/TR/owl-features/">Web Ontology
      Language</a> (OWL) for the target dialect of XML used in this
      export schema.
      <br />
       Words and Terms come from, and are uniquely identified by
      the existing wordnet vocabulary, and their relationships are
      described using the <a
      href="http://www.w3.org/TR/rdf-schema/">RDF Schema</a>
      'ParentOf' and 'ChildOf' terms etc.
    </p>
    <p>
      This modification of the taxonomy_xml.module is intended for
      two uses.
    </p>
    <ol>
      <li>
        To assist in migrating taxonomies between cloned sites, eg
        dev and live copies of essentially the same site. To this
        end, some effort has been put into maintaining vocabulary
        IDs and term IDs, because once they get out of synch,
        cloning and replication is almost a lost cause.
      </li>
      <li>
        To become a foundation for a Taxonomy Interchange
        initiative [<a
        href="http://www.iandickson.com/taxonomy/drupal/node/38">Taxonomy
        Server</a>] and therefore, I guess, somewhat similar to all
        those other 'taxonomy warehouses' <em>but</em> we intend to
        publish, for import/export, these shared taxonomies in a
        way that allows Drupal sites (or other related
        technologies) to share this data.
      </li>
    </ol>

    <br />
     
    <h2>
      Sources of Taxonomies
    </h2>
    The following sites provide downloadable taxonomies, Thesauri
    or Glossaries that are at least partly compatable with this
    import tool. 
    <ul>
      <li>
        <a
        href="http://www.w3.org/2003/03/glossary-project/data/glossaries/">
        W3C Glossary Project</a> (RDF downloads) (Also <a
        href="http://www.w3.org/2003/glossary/">browsable</a>
      </li>
      <li>
        <a
        href="http://www.e.govt.nz/standards/nzgls/thesauri/downloads.html">
        Subjects of New Zealand (SONZ) and Functions of New Zealand
        (FONZ) thesauri</a> (CSV Downloads)
      </li>
      <li>
        <a
        href="http://www.eionet.europa.eu/gemet/rdf?langcode=en">GEMET
        provides multilingual versions of extensive topics</a>
        (SKOS/RDF fractured Downloads - labels are in one file,
        relationships in another etc) Also browsable
      </li>
    </ul>
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